Equipment for the controlled and uniform cooking of foods of lesser thicknesses

ABSTRACT

Equipment for the controlled and uniform cooking of foods of lesser thickness so that cooking occurs uniformly on the whole upper surface of the food and uniformly on the whole lower surface of the food comprising a base having a hole; a lower burner disposed below the hole; a heat conducting plate disposed over the hole, a lower surface of food resting on the plate being uniformly cooked by the thermal conduction from the lower burner through the plate; a chamber having an open bottom spaced from the plate; an upper burner disposed in the chamber; a fume deflector device mounted to the chamber and mounted between the upper burner and the heat conducting plate for deflecting and evenly distributing hot fumes generated by the upper burner so that a uniform column of hot fumes descends vertically toward the heat conducting plate and strike perpendicularly over an upper surface of food resting on the plate; and a deflector ring encircling and concentric with the chamber and having a lower end in contact with at least one of the plate and the base, the deflector ring being spaced from and mounted to the chamber so as to define an annular-shaped gap therebetween, whereby hot fumes, after striking the surface of food resting on the plate, are conveyed away from the plate.

The present invention refers to a process and equipment to cook, roast,brown and to carry out other cooking operations, in a uniform and rapidmanner, of the complete upper surface of foods of lesser thicknesses insuch a way that all points of this surface attain the same degree ofcooking and the same occurs at all points of the lower surface, alsoallowing that the degree of cooking to be reached by the two surfaces bethe same or, if necessary, different.

The cooking processes, as known today, started with the archaicreverberatory wood stove, which required constant movement by rotationor shifting of the foodstuff on the heating surface in order to try andobtain uniform cooking between the upper and lower surfaces as well asuniform cooking at all points of the same surface. This movement isnecessary because this type of oven gives a horizontal motion of the hotfumes, produced by the flame, towards the flue located in the oppositeposition sweeping over the surface of the food in only one direction.This oven, of low thermal output is anti-economic, besides requiring aspecialized operator looking after it continuously, has the onlyadvantage of providing quick cooking at the expense of an enormous wasteof thermal energy.

Gas stoves, where all the heat is produced inside a chamber by means ofone or more burners have, in common, the characteristic of mixing thefumes and heat from the various burners so that the circulation of thefumes and vapours, acting in accordance with the laws for the naturalrising of hot fumes, result in the formation of heterogeneous risingcolumns giving non-uniform cooking between the outer surface and thecentre and between the upper and lower parts of the foodstuff, acondition proven in the new models of ovens which are provided withturbines and/or ventilators so as to cause a turbulence to the risingfumes in an attempt to obtain a uniform distribution of the heat foruniformity in cooking.

Even electric ovens present problems with respect to the uniformity inthe cooking. The type with a metallic chamber of low thermal inertiarequires the use of turbines or homogenizing ventilators because theformation of the ascending column is its negative characteristic,analogous to the previous case above mentioned. Those of a high thermalinertia type with resistances outside the refractory chamber, are alsodeficient with regard to uniformity and, equal heating between the upperand the lower part, which is in contact with the base plate, isdifficult because the sequence of cooking successive pieces provokescooling of the base plate which, due to its poor conductivity associatedwith the unfeasibility of very high momentary potentials, does not allowthe base plate to regain the temperature after being cooled by the piecebeing removed.

Micro-wave ovens also require, in order to obtain uniform cooking,constant movement of the foodstuff during cooking, this beingcorroborated in that the latest models are equipped with a motorizedrotating plate, so as to move the food during the time it is beingcooked.

Besides, this type of oven does not roast or brown the foodstuffs.

On the other hand, every type of oven now existing destined for thecooking of foodstuffs has access to the interior of the oven by means ofa vertical front door which facilitates the introduction and removal ofthe material to be cooked; however, they are deficient as to theuniformity of cooking since the existence of the door in this positionalways causes, even on a small scale, more intensive cooking in the zonefarthest from the door.

It is the object of the present invention to eliminate theinconveniences, mentioned above, of the processes and equipments forcooking actually being used and to obtain quicker cooking even with lowpotential, besides very high thermal and economic yield dispensing withany handling of the foodstuff during cooking and doing without a specialoperator. These objectives are attained with the process now developedand the respective equipment, which is not a mere improvement of thoseexistent but a substantially new development.

In the process of the present invention, the heating of the upperportion of the foodstuff is accomplished by a descending, vertical andhomogeneous (thermally and dynamically fluid) column of hot fumes and byinfra-red radiation. Both the descending column of hot fumes and theinfra-red radiation of uniform superficial density, are furnished by agas burner and its respective fume deflector, located necessarily insideand in the upper part of the chamber, which is closed on top and open onthe bottom. In this way, the column is obliged to descend and reachperpendicularly the top face of the foodstuff placed next to thehorizontal opening of the chamber and in a horizontal position, when andwhere there is the transfer of heat from the fumes to the upper face ofthe food which in turn forces the fumes, at point of contact with thefoodstuff, to take a radially horizontal path until they leave thechamber by the outside walls this being the only possible escape andwhere an annular deflector sends the fumes upwards and out to theatmosphere.

Since the pressure exercised by the hot fumes in the upper part of thechamber (where it is closed), is greater than the atmospheric pressureit becomes necessary that the gas/air blender which supplies the burner,has the capacity to overcome this counter-pressure against the flame,thus requiring a mixer of the Venturi type of good efficiency which canalso be aided by an outside exhaust deflector ring, if this hassufficient height to contribute to the removal of the fumes, thusconstituting an annular chimney concentric with the chamber.

This process of heating by a jet, directed perpendicularly to thesurface of the foodstuff placed in a horizontal position, gives to thecooking of the upper part of the foodstuff exceptional characteristicsof uniformity, because the hot fumes, after giving up their heat to thefood, are themselves deviated in a direction perpendicular to theinitial and routed to the outside of the chamber where they leave in auniform stream, that is, in constant discharge at all points on theoutside at the mouth of the chamber.

As regards cooking of the lower part of the foodstuff, the processconsists in heating this by an external and consequentially independentburner, by means of a high thermal conductivity plate which supports thefoodstuff and is placed horizontally next to the horizontal opening ofthe above-mentioned oven, functioning also as a tray, base plate anddoor of the oven, simultaneously.

The equipment to carry out the process of the present invention is madeup of two sets and one piece, as follows:

one set which we will call the oven;

another set which we will call the external heater;

one piece which is the supporting tray for the foodstuff being at thesame time the base plate and door of the oven for it carries out thesevarious functions simultaneously.

The set denominated oven is constituted essentially of:

a chamber with a horizontal opening on the bottom;

a gas/air mixture burner;

a flame deflector and also an infra-red radiation emitter;

an external vertical deflector ring, open at both extremities, when theoven remains open.

The equipment denominated external heater set of the oven door, alsocalled lower set is essentially made up of:

a horizontal table, with a lid open in the centre to act as a bed forthe tray;

a burner located below the lid of the table centered with the opening inthe lid.

The equipment completed in working position presents its threecomponents described above, placed together in the following manner topto bottom: the oven is placed over the tray which supports the foodstuffand this is centered and resting on its bed over the external heaterset.

This and other characteristics of the process and its respectiveequipment, object of this present invention, besides its advantages willbe made evident in greater detail in the description that follows whichis given as a non-restrictve example, and through the attached drawingswhich are also non-restrictive, in which:

FIG. 1 - Schematically illustrates, in cross section, the completeequipment mounted in the closed position (working position).

FIG. 2 - Shows in a lateral view, the complete equipment in the openposition, with the tray out of position.

FIG. 3 - Shows in cross section the upper part of the oven.

FIG. 4 - Shows in a partial cross section one of the many possible formsof the equipment denominated oven.

FIG. 5 - Illustrative plan of one of the many possible forms of the foodcarrying tray.

FIG. 6 - Lateral view of the food carrying tray, shown in FIG. 5.

FIG. 7 - Lateral view of one of the possible forms for the food carryingtray.

FIG. 8 - Lateral view of another possible form for the food carryingtray.

FIG. 9 - Illustrates in a partial cross section one of the many possibleforms of the mouth of the oven's chamber.

FIG. 10 - Shows a partial cross section of another of the possiblemultiple forms of the mouth of the oven's chamber.

FIG. 11 - Shows a partial cross section of another example of thepossible multiple forms of the mouth of the oven's chamber.

The external heater set of the tray, door and base plate (1) of the oven(shown in FIGS. 1 and 2) is a fixed set constituted of one burner (2),with flame directed upwards, located and fixed firmly, at a convenientdistance, in the lower part of the table top (3). Besides this, thecentre of the burner (2) is located on the vertical which passes throughthe centre of the hole (4) of the table top (3). This burner (2)receives by means of a tube (5) a gas/air mixture in stechiometricproportion or with an excess of up to 20% of air coming from a mixer,for example of the Venturi type, fed and controlled by a pressureregulator and its respective manometer connected to a solenoid valvecommanded by a timer, instruments sufficiently well known and not shown.Ignition is produced by a spark plug (6), the spark of which is provokedby a conventional sparker and is also controlled by the timer, allmentioned and not shown.

FIGS. 3 and 4 show one of the possible forms of the set denominatedoven, where we can see the external deflector ring (7) which encirclesconcentrically and at a small distance from the lower surface of thechamber (8) and firmly fixed to it by means of spaced bolts (9). Thisconcentric association between the chamber (8) and the externaldeflector ring (7) determines the annular-shaped gap (10) between them,through which gap the fumes and vapours are expelled from the chamber(8). As shown in FIG. 1 the heating inside the chamber (8) is done by aburner (11), located obligatorily in its upper part. If the flameproduced by this burner (11) is directed downwards it is necessary tohave a fume-deflector (12) whose purpose is to provoke turbulence andhomogenization of the descending column of hot fumes and concomitantlyproduce infra-red radiation. If, optionally, the flame is directed inany other direction which is not down. The presence of thefume-deflector (12) may not be necessary. However, the thermal outputwill be prejudiced and considerably diminished. The supply of thegas/air mixture for this burner (11) is made through the tube (20) andin the manner and proportions identical to those of the external burner(2) already mentioned, but independently of it. In the same way,ignition is made by means of a spark plug (13), whose sparking isproduced and controlled by the same equipment of the external burneralready described and not shown.

FIG. 1 shows the coupling of the oven proper with the tray (1) and theexternal burner kit. In this situation, the food carrying tray (1) hasmultiple functions, serving at the same time as the entrance to theoven, base plate of the oven and closure of the lower opening (14) ofthe external deflector ring (7). The coupling between the oven and theexternal burner kit is made, for example, by means of an articulation inthe form of a hinge (19) located in the back section of the top (3) ofthe table which makes possible the rotation of the oven around thehorizontal axle of the hinge (19), once the handle (17) is manipulated.The oven remains in the open position as shown in FIG. 2 by means of theprop (16).

As illustrated in FIGS. 1 and 2 with the tray (1) carrying the food (15)already in working position, centralized in the hole (4) of the top (3)the prop (16) is removed and the oven is lowered by the handle (17)until it rests on the aforesaid tray (1). At this stage the upperburners (11) and the lower burner (2) are lit and cooking of the food(15) starts. Its upper part is cooked exclusively and uniformly throughthe action of the descending hot fumes and it is possible also toassociate this with or without the action of infra-red radiation. Thedescending hot fumes after striking the food (15) are deflected by thesame to the periphery of the entrance (18) of the chamber (8) where theyexit horizontally being then deflected by the external deflector ring(7) and expelled vertically upwards through the annular-shaped gap tothe outside atmosphere. When associated with cooking by infra-redradiation, this will be produced by heating the deflector (12) locatedbelow the flame of the burner (11). This uniform density radiation canbe regulated in intensity by varying the distance of the deflector (12)from the flame. The lower part of the food (15) is cooked exclusively bythe hot fumes of the lower burner (2) which transfers its heat to thebottom part of the tray (1), made of good heat-conducting material.

This particular set-up assures that there isn't any interference betweenthe hot fumes coming from the two distinct heat sources, as well asclearly defining the separate zones for the cooking of the food (15)which is provided by the tray (1).

Once the pre-determined time has elapsed, the timer deactivates thesolenoid valve which, in turn, shuts off the passage of gas thusshutting off all burners (11) and (2).

Lifting up the oven by means of the handle (17) and fixing it in an openposition as shown in FIG. 2 using the prop (16), the tray with the food(15) already cooked is removed. The equipment is ready to receive a newlot of uncooked food and to repeat the work cycle.

The process and equipment for the controlled and uniform cooking, offoods of lesser thicknesses, of the present invention offers thefollowing advantages over present systems:

produces absolutely uniform cooking to all parts of every surface of thefood;

the upper and lower surfaces are cooked equally and when necessary,cooked unequally by the equipment due to its exclusive characteristic ofpresenting independence of action and effect by the two heat-generatingsources--one by means of a descending column of fumes and infra-redradiation over the upper surface of the food and the other external,heating the lower part of the food exclusively by conduction through athermally conductive plate;

in the specific case of foodstuffs which have substantially differentcompositions between the upper and lower layers, that is, asymmetric(al)as to the degree of hydration, as for example, the presence of sauces ona layer of dough of fermented wheat flour, we get controlled andadequate cooking in spite of the heterogeneous make-up of the materialsused, not only by regulation of the burners but by varying thepercentage of emission of infra-red radiation, exclusive characteristicof this equipment;

one important advantage of this equipment is that it cooks in less timethan existing equipment. To achieve the same type of cooking in anexisting oven takes, for example, 10 to 20 minutes whilst the equipmentof this invention will do this in about 90 seconds. This enormousreduction in cooking time confers, in certain cases, greater appetizingproperties than with slower cooking, besides a considerable economy offuel, chiefly when the equipment is used in industrial activities wheretime is money;

this process and equipment for heating gives high thermal yield andconsequently economy, propitiated by its various characteristics:

(a) when the arrangement of the external deflector ring (7) whichencircles all the chamber (8) acts to minimize the heat loss from thewall of the chamber since in this way the external wall of the chamber(8) is heated by the fumes which flow through the annular gap (10)having, however, a small temperature gradient between the internal andexternal wall surfaces of the above-mentioned chamber;

(b) through the fact that the heat of the descending fume column istransferred obligatorily to the food, almost in its entirety, beforeleaving the chamber (8).

(c) the low calorific capacity of the apparatus allows thermalequilibrium to be reached in about 60 seconds which clearly demonstratesthat the quantity of heat absorbed by the equipment mass is minimal,concluding therefore that the overall heat loss is a minimum;--besidesthis, the equipment is extremely light making it easily transportable,of simple and economic construction and not requiring a specializedperson to operate it.

Naturally, the invention disclosed above is not limited to theprocedures described and illustrated and can be fully varied andmodified in the construction of the various component parts, withoutlosing its technical characteristics.

We claim:
 1. Equipment for the controlled and uniform cooking of foodsof lesser thickness so that cooking occurs uniformly on the whole uppersurface of the food and uniformly on the whole lower surface of thefood, comprising:a base having a hole; a lower burner disposed belowsaid hole; a heat conducting plate disposed over said hole, a lowersurface of food resting on said plate being uniformly cooked by thermalconduction from said lower burner through said plate; a chamber havingan open bottom spaced from said plate; an upper burner disposed in saidchamber; a fume deflector means mounted to said chamber and mountedbetween said upper burner and said heat conducting plate for deflectingand evenly distributing hot fumes generated by said upper burner so thata uniform column of hot fumes descends vertically toward said heatconducting plate and strike perpendicularly over an upper surface offood resting on said plate; and a deflector ring encircling andconcentric with said chamber and having a lower end in contact with atleast one of said plate and said base, said deflector ring being spacedfrom and mounted to said chamber so as to define an annular-shaped gaptherebetween, whereby hot fumes, after striking the surface of foodresting on said plate, are conveyed away from said plate.
 2. Equipmentas in claim 1 wherein said fume deflector means provokes turbulence andhomogenization of hot fumes generated by said upper burner.
 3. Equipmentas in claim 2 wherein said deflector means includes means for producinginfrared radiation upon exposure to hot fumes from said upper burner. 4.Equipment as in claim 1 further comprising:means, connected between saidbase and said deflector ring and said chamber, for allowing saiddeflector ring and said chamber to pivot away from said base; and meansfor propping said deflector ring and said chamber while pivoted awayfrom said base.
 5. Equipment as in claim 1 further comprising means forproducing sparks disposed near said lower burner and said upper burner.